During normal operation of a mine, material is constantly being generated that needs to be removed from the mine workings. For example, in drill-and-blast mining, the fragmented rock or muck that is generated after the blast needs to be removed in order for advancement of the tunnel to occur. In continuous drilling and mechanical rock cutting methods, significant amounts of fragmented rock have to be removed. Furthermore, raiseboring activities that generate new vertical shafts to the mines generate fragmented rock that needs to be removed.
In most cases, the material generated from such activities has been removed from mine workings by being vertically hoisted in a shaft with a suitable conveyance. For example, mine-shaft elevators are typically loaded with the fragmented rock and hoisted to the surface for further processing. At mine locations where there is ramp access, fragmented rock can be removed with a conveyor belt or with a fleet of trucks.
Hydraulic hoisting systems have also been considered for removing material from an underground mine. Essentially there are two categories of hydraulic hoisting systems, pumping systems and feeder systems (see van den Berg G and Cooke R, “Hydraulic Hoisting Technology for Platinum Mines”, presented at the Platinum Adding Value Conference 2004).
Pumping systems involve using a pump or multiple pumps to energize a slurry containing the fragmented rock or ore to travel through a mostly vertical conduit to be deposited at the surface. In these applications, the pump responsible for moving the slurry resides in the mine and is connected to the slurry preparation unit. Moreover, the slurry is in direct contact with the pump.
In feeder systems, on the other hand, the slurry is isolated from the pumping equipment by some form of feeder or pressure exchange system. In such systems, a low pressure pump is typically required to supply the feeder.